A dosing system with a gear rack is known from European patent document B1 0,037,696. This system has the disadvantage that, by pressing the dosing button more than once, the patient may self-administer a medical overdose. Another disadvantage is that, as a rule, the proper dose is administered by moving forward several gear teeth, and that reciprocation of the dosing button in the longitudinal direction of a dosing stroke may result in overdosing.